Word watching: Single or double consonant?

Deciding whether to double the final consonant of a word before adding ed or ing is a common problem. Grouping the words that take these endings according to how they are accented makes learning and remembering the correct spellings easier. More than 100 verbs are grouped into seven categories. One of the more difficult to remember categories is guided by this rule: If the accent is on the first syllable, almost always a single consonant precedes the -ed and -ing forms.